A contribution to the cathodoluminescence analysis of commercial batio3ceramic devices

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Abstract
The combination of scanning electron microscopy with integral and spectral cathodoluminescence (CL) measurements has proved to be a very valuable measuring method to analyse the grain boundary structure of laboratory-made barium titanate ceramics (LBTC), enabling an experimental confirmation of some important aspects of existing theories of the PTC effect. The CL measuring technique should additionally open the possibility for the quality control of commercial barium titanate ceramics (CBTC). Corresponding studies were performed. Unexpectedly and in contradiction to the results gained for LBTC, it was found that in integral CL images of CBTC, the BaTiO3 grain boundary zones appear to be light, the grain interior dark. Moreover a definite correlation between the local CL distribution and specimen regions of high and low pore density can be observed. The CL spectra of CBTC show additional peaks. The spectral composition is also connected to pore-rich and pore-free specimen regions. In this study, these differences are discussed in terms of the local barium vacancy distribution and of the presence of particular metal impurities in the material. For complete understanding, however, further microanalytical investigations are required.